I think that some of the people posting on this thread have different understandings of the question "is it necessary to balance the rudder?"
Some people read that question as meaning "is it necessary to add sufficient balance weight so the rudder is balanced about the hinge line, just like the elevators?"
Other people read that question as meaning "is it necessary to install the balance weight that Van calls for in the plans, or can I safely leave it off?"
Build the rudder with the balance weight that Van's supplies. They have done the engineering and flight testing to show that the supplied weight provides adequate flutter protection. There is no need to add additional weight so the rudder is 100% balanced.
On the other hand, if you leave the weight off, you have no idea whether the rudder will flutter inside the approved speed envelope, or not. Flutter, if it occurs, will likely lead to loss of the rudder and possibly the VS, likely leading to a fatal accident.
Build the aircraft as called for in the plans.